Project Summary The molecular mechanisms of prostaglandin action are of considerable importance to reproductive biologists, immunologists, neurobiologists, and oncologists. Aspirin and other non-steroidal anti- inflammatory drugs (NSAIDs) specifically inhibit prostaglandin synthesis and are associated with cancer prevention and reversible infertility. Prostaglandins are essential for ovulation and fertilization, but the molecular mechanisms are not well understood. The mouse is the only genetic system currently available to study prostaglandin functions during reproduction. The objective of this application is to determine the extent to which the nematode model Caenorhabditis elegans can be used to address fundamental questions in prostaglandin biology. To achieve this objective, we will test the central hypothesis that oocytes synthesize prostaglandins to regulate ovulation and sperm guidance. Support for this hypothesis comes from preliminary data showing that prostaglandin precursors, polyunsaturated fatty acids (PUFAs), and predicted prostaglandin synthases are required for these processes. In addition, prostaglandins can regulate sperm motility in the absence of PUFAs. Our first aim is to delineate a prostaglandin biosynthesis pathway that functions in oocytes. To achieve this aim, we will characterize predicted prostaglandin biosynthesis enzymes at the genetic and biochemical levels. Our second aim is to determine the extent to which prostaglandins and NSAIDs influence fertilization. To achieve this aim, we will examine the effects of prostaglandins and NSAIDs on sperm motility and ovulation in vivo. Our final aim is to identify the PUFA-derived signals synthesized by oocytes. A combination of genetics and liquid chromatography coupled to electrospray ionization tandem mass spectrometry will be used to achieve this aim. We expect that completing the proposed aims will establish the C. elegans gonad as the first simple, genetically tractable model for discovering molecular mechanisms of prostaglandin action during reproduction. These studies should lead to a comprehensive delineation of genes that are required for prostaglandin synthesis and function, any of which could encode new drug targets. The role of prostaglandins in fertilization could be conserved in mammals, an idea supported by prostaglandin deficient mice. Regardless, basic research on prostaglandins in the C. elegans gonad has the potential for discovering molecular mechanisms of human infertility, contraception, and cancer.